The current invention relates to fuel systems which employ two different types of fuels supplied in a common fuel rail to common fuel injectors.
Bi-fuel systems have been used in engines of motor vehicles to provide alternative power supplies to the engine. The fuels used are typically gasoline and a low pressure gas, such as propane. Benefits of this type of system include the ability to select a fuel which produces generally a lower amount of unwanted emissions but is generally less readily available, such as propane, or a more readily available fuel but which produces higher amounts of unwanted emissions, such as gasoline. Most fuel injectors which have been designed for use with gasoline are not designed for use with a low pressure gas. Therefore, to use a bi-fuel system, separate fuel injectors for each of the two types of fuels must be installed for each combustion chamber of the engine. Each set of fuel injectors must be supplied by a separate fuel rail. As a result, when the low pressure gas supplies the fuel, the gasoline injectors are not flowing any fuel. Stagnant fuel inside the gasoline injectors is exposed to elevated temperatures for extended period of time, which can aggravate deposit formations and negatively affect emissions.
Additionally, the requirement for separate fuel injectors, as well as separate fuel rails adds to the cost and weight of the fuel system, making the bi-fuel system a less attractive alternative to a single fuel system.
It would be beneficial to develop a fuel system in which a liquid fuel, a low pressure gas fuel, or a mixture of the two types of fuels can be used in a single set of fuel injectors which are supplied by a common fuel rail. Such a system would allow either the liquid, the gas, or the mixture to be used in a single fuel system, reducing the weight and cost of such a fuel system.
A fuel system for an internal combustion engine is provided. The engine has a plurality of combustion chambers. The fuel system comprises a liquid fuel and a low pressurize gaseous fuel. The fuel system further comprises a fuel tank, with the liquid fuel and the low pressurize gaseous fuel forming a fuel mixture in the fuel tank. A single fuel supply rail is fluidly connected to the fuel tank and a fuel injector fluidly connects the single fuel supply rail to each of the plurality of combustion chambers. The fuel mixture is provided to each fuel injector for injection into each respective combustion chamber.
A fuel system for an internal combustion engine having a plurality of combustion chambers is also provided. The fuel system comprises a fuel tank adapted to receive a mixture of a liquid fuel and a low pressurize gaseous fuel. A single fuel supply rail is fluidly connected to the fuel tank. A fuel injector fluidly connects the single fuel supply rail to each of the plurality of combustion chambers.
A method of operating a bi-fuel system is also provide. The method comprises supplying the mixture to a single fuel supply rail; directing the mixture through the single fuel supply rail to a plurality of fuel injectors; directing at least part of the mixture into each of the plurality of fuel injectors; directing a remaining part of the mixture to a single fuel return rail; and returning the remaining part of the mixture to the common tank.